Fire resistant air transfer grille or damper

ABSTRACT

A fire resistant air transfer grille or damper ( 10 ), suitable for use as a ventilating means in fire resistant doors, walls and ventilation ducts, includes an outer frame ( 12 ) and a plurality of slats ( 14 ). Each of the slats ( 14 ) is provided with an intumescent core and is positioned in one of a number of predetermined positions within the outer frame ( 12 ). The predetermined positions are determined by a number of recesses ( 26 ) provided in the outer frame ( 12 ). The outer frame ( 12 ) may be formed as two separate frame components ( 16, 18 ), and is preferably made from steel. The slats ( 14 ) are preferably formed from aluminium with an intumescent material provided within the aluminium slat ( 14 ) to provide an intumescent core. Each of the slats ( 14 ) also preferably includes an elongate channel member ( 30, 32 ) along each of two of its side edges, wherein the elongate channel members ( 30, 32 ) of each of the slats ( 14 ) engage within the recesses ( 26 ) in the outer frame ( 12 ).

The invention relates to an improved fire resistant air transfer grilleor damper, used particularly, but not exclusively, as ventilation meansin fire and smoke resistant doors, walls and ventilation ducts.

Large buildings, especially industrial buildings, are often split into anumber of self-contained areas by fire and smoke resistant walls anddoors. It is often necessary to ventilate these areas, and hence anumber of air transfer grilles or dampers are required to allow thethrough flow of air into and out of the self-contained areas.

However, in the event of a fire, these air transfer grilles or dampersalso allow the through flow of smoke, hot gases and in extremesituations, flames.

It is thus desirable to use an air transfer grille or damper that doesnot allow the through flow of smoke, hot gases and flames in the eventof a fire. Such an effective air transfer grille is one thatincorporates a plurality of slats, wherein each of the slats has anintumescent core.

When used in fire and smoke resistant walls and doors defining a room orother distinct area, air transfer grilles or dampers incorporatingintumescent slats allow the through flow of air in and out of the room.

In the event of a fire, high temperatures cause the intumescent slats toswell to many times their original thickness, fusing together to form anon-combustible mass which provides fire resistance to match thesurrounding construction and prevent the through flow of hot gases,smoke and flames.

The intumescent slats may be provided with elongate reinforcing channelsas protection along their edges. Hitherto the channels have been weldedinto position within an outer frame by spot welds, as shown in FIGS.5-8. The use of spot welds in the manufacture of such grilles ordampers, however, is expensive due to the number of spot welds required,and the jigs required for each different size grille.

According to an aspect of the invention, there is provided a fireresistant air transfer grille or damper comprising:

a frame defining a gas transfer path, the frame including two opposedwall portions, each including at least one recess;

a slat including a core of intumescent material and having at least oneelongate edge whereby the or a said edge is receivable at either end ofthe slat in a pair of the recesses respectively in the opposed wallportions; and

a retainer for retaining the slat in the said recesses whereby the slatpermits gas flow along the gas transfer path when unswollen and closesthe gas transfer path on tumefaction.

An advantage of the invention is that spot welds are not required tosecure the slat into position, as the slat is retained in positionwithin recesses in the opposed wall portions of the frame by a retainer.This provides a much simpler method of assembly, and also provides amore robust product in use, as the risk of weld failure is removed.

In a preferred embodiment of the invention the retainer is a mirrorimage of the frame and so includes two opposed wall portions that eachinclude at least one recess. In this preferred embodiment, the slat hasa second elongate edge that is receivable at either end of the slat in apair of the recesses respectively in the opposed wall portions of theretainer.

The frame and the retainer may be secured together by securing means,and are preferably secured together by a number of sleeve-bolts insertedthrough apertures in the retainer and the frame.

The use of sleeve-bolts prevents deformation of the frame componentswhen the bolts are tightened.

An elongate channel member may be provided on the or each of theelongate edges of the slat. These elongate channel members protect theelongate edges of the slat that are receivable in recesses in the frameand, when required, in the retainer.

Preferably the elongate channel members are made from steel.

In a further embodiment of the invention, a plurality of slats eachincluding a core of intumescent material and having at least oneelongate edge are included within the fire resistant air transfer grilleor damper. In this embodiment of the invention, the opposed walls of theframe each include a plurality of recesses and the or a said elongateedge of each of the plurality of slats is receivable at either end ofthe slat in a pair of recesses respectively on the opposed wallportions. The retainer retains the slats in the recesses, and in apreferred embodiment, the retainer is a mirror image of the frame andthe slats each include a second elongate edge. The second edge of eachof the plurality of slats is then receivable at either end of the slatin a pair of recesses respectively on opposed wall portions of theretainer.

In embodiments of the invention where the fire resistant air transfergrille or damper includes a plurality of slats, the or an elongate edgeof each of the slats may be received at either end of the slat in a pairof recesses respectively so that the slats are arranged parallel to eachother.

The frame and retainer may be rectangular in shape so producing arectangular fire resistant air transfer grille or damper. The slat orslats may also be rectangular, each slat then having two elongate edgesextending parallel to each other.

The slats may be made from PVC or metal with an intumescent materialprovided within the slat to provide an intumescent core.

Preferably the slats are made from aluminium with an intumescentmaterial provided within the aluminium slat to provide an intumescentcore.

The aluminium acts as a protective layer and gives a quick sealingresponse and added resistance to erosion of the intumescent materialwhen subjected to high velocity hot gases.

In preferred embodiments, the outer frame is made from steel. Such anouter frame contributes to fire performance by preventing inwarddeformation of surrounding structures and protecting the intumescentmaterial within the grille or damper.

The use of a fire resistant air transfer grille or damper according to apreferred embodiment of the invention has been found to provide fireresistance of up to four hours, and consistently achieve a complete sealin two minutes, when tested in accordance with BS 476 Parts 20 and 22,and similarly internationally recognised standard methods of test. Insome circumstances a complete seal is achieved in as little as ninetyseconds.

An embodiment of the invention has also been found to be resistant tothe onerous impact, erosion and cooling effects of the “Hose Stream”test applied after exposure to typical American fire test regimes suchas UL 10C.

According to a further aspect of the invention there is provided amethod of manufacturing a fire resistant air transfer grille or damperincluding the steps of:

positioning a slat including a core of intumescent material and havingat least one elongate edge, so that the or a said edge is received ateither end of the slat in a pair of recesses respectively in opposedwall portions of a frame; and

positioning a retainer so that it retains the slat in the said recesses.

An example of a fire resistant air transfer grille or damper accordingto an embodiment of the invention will now be described, by way of anon-limiting example, with reference to the following figures in which:

FIG. 1 is a perspective view of a fire resistant air transfer grille ordamper according to an embodiment of the invention;

FIG. 2 shows the air transfer grille or damper of FIG. 1 along the lineI—I;

FIGS. 3 and 4 show parts of the FIG. 2 arrangement in more detail;

FIG. 5 is a perspective view of a prior art fire resistant air transfergrille or damper including a plurality of slats secured into position byspot welds;

FIG. 6 shows the fire resistant air transfer grille or damper of FIG. 5along the line II—II; and

FIGS. 7 and 8 show parts of the FIG. 6 arrangement in more detail.

A fire resistant air transfer grille or damper 10 (herein “air transfergrille 10”) according to an embodiment of the invention is shown in FIG.1.

The air transfer grille 10 includes an outer frame 12 and a plurality ofslats 14 positioned at predetermined positions within the outer frame12.

Either side of the outer frame 12 is open, so that in use, air can passbetween the slats 14 in the grille 10.

The air transfer grille 10 shown in FIG. 1 is rectangular, but it willreadily become obvious to a skilled reader how, within the scope of theinvention, to produce an air transfer grille 10 of other shapes.

The outer frame 12 of the air transfer grille 10 is made up of twoidentically shaped and dimensioned frame components 16,18.

Each of the frame components is formed from four generally L-shapedframe members 20 a-20 d that are preferably welded together.

In other embodiments, the four generally L-shaped frame members 20 a-20d may be mechanically fastened together.

Due to the nature of the generally L-shaped frame members 20 a-20 d,each of the frame components 16,18 has a front edge 22 that extendsaround the perimeter of the frame component, and a side edge 24 thatextends away from, and perpendicular to, the front edge 22.

The front edge 22 of each of the frame components 16,18 surrounds theopening through which, in use, air flows through the air transfer grille10.

Two parallel sides 22 a,22 b of the front edge 22 are provided with aplurality of equidistantly spaced recesses 26. The recesses 26 in thisembodiment are formed in a lip 28 that is upstanding an inner edge ofthe front edge 22 on the two sides 22 a,22 b.

Pairs of the recesses 26 on each of the parallel sides 22 a,22 b arealigned with each other.

The slats 14 that are used in the air transfer grille 10 shown in FIG. 1each take the form of a rectangular strip. The shape of the slats 14 isdependent upon the shape of the outer frame 12 of the air transfergrille 10.

The slats 14 preferably include an aluminium membrane surrounding anintumescent material to provide each of the slats 14 with an intumescentcore.

In other embodiments, the slats 14 may include a copper membrane.

The slats 14 shown in FIGS. 1 to 4 each include two elongate retainersor channel members 30,32, that extend along two parallel sides 34,36 ofeach of the slats 14 respectively.

In a preferred embodiment of the invention, the elongate channel members30,32 and the outer frame 12 of the air transfer grille 10 are made fromsteel.

To construct the air transfer grille 10, the slats 14 are positioned sothat one (30) of each of the elongate channel members 30,32 of each ofthe slats 14 extends between, and engages within, two correspondingrecesses 26 of one (16) of the frame components 16,18.

The slats 14 extend generally perpendicular to the frame component 16 sothat the other elongate channel member 32 of each of the slats 14 canextend between, and engage within, two corresponding recesses 26 in theother frame component 18.

In use, the two frame components 16,18 are secured together, in anopposite orientation to each other, so that the side edges 24 of each ofthe frame components 16,18 meet each other, and the front edges 22 areon the outside of the completed air transfer grille 10.

The two frame components 16,18 are preferably secured together by foursleeve-bolts 36, each sleeve-bolt passing from an aperture in one of thecorners of the front edge 22 of one (16) of the frame components 16,18,to an aperture in the corresponding corner of the front edge 22 of theother frame component 18.

The sleeve 38 of each of the sleeve-bolts 36 extends between the frontedges 22 of the two frame components 16,18 so that over-tightening ofthe bolt 40 is prevented, and the front edges 22 of the frame components16,18 do not become distorted.

What is claimed is:
 1. A fire resistant air transfer grille or damper,comprising: a frame defining a gas transfer path and a plurality ofslats extending across the path, the frame being formed by a framecomponent and a retainer which are secured together, the frame componentincluding two opposed wall portions each including a plurality ofrecesses; each slat including a core of intumescent material and havingat least one elongate edge, whereby the edge of a slat is receivable ateither end of the slat in a pair of the recesses respectively in theopposed wall portions; and securing means for securing the framecomponent and retainer together in order to retain each slat in the saidrecesses, whereby the slats permit gas flow along the gas transfer pathwhen unswollen and close the gas transfer path on tumefaction.
 2. A fireresistant air transfer grille or damper according to claim 1 whereineach opposed wall portion comprises an L-shaped frame member having alip in which said recesses are formed.
 3. A fire resistant air transfergrille or damper according to claim 1, wherein the retainer includes twoopposed wall portions that each include a plurality of recesses, eachslat having a second elongate edge that engages within a pair ofrecesses in the retainer when the retainer retains each slat in therecesses in the frame component.
 4. A fire resistant air transfer grilleor damper according to claim 1, wherein the securing means comprise anumber of sleeve-bolts inserted through apertures in the retainer andthe frame component.
 5. A fire resistant air transfer grille or damperaccording to claim 1 wherein a retainer is provided on each of theelongate edges of each slat.
 6. A fire resistant air transfer grille ordamper according to claim 1, wherein the slats are arranged parallel toeach other.
 7. A fire resistant air transfer grille or damper accordingto claim 1, wherein the frame component and retainer are rectangular inshape, producing a rectangular air transfer grille.
 8. A fire resistantair transfer grille or damper according to claim 1, wherein each slat ismade from one of PVC or metal, with an intumescent material providedwithin the slat to provide an intumescent core.
 9. A fire resistant airgrille or damper according to claim 8, wherein each slat is made fromaluminium with an intumescent material provided within the aluminiumslat to provide an intumescent core.
 10. A fire resistant air transfergrille or damper according claim 1, wherein each slat is rectangular andis provided with two parallel elongate edges.
 11. A method ofmanufacturing a fire resistant air transfer grille or damper inaccordance with claim 1, including the steps of: positioning a pluralityof slats each including a core of intumescent material and having atleast one elongate edge, so that the edge of each slat is received ateither end of the slat in a pair of recesses respectively in opposedwall portions of a frame component; positioning a retainer so that itretains the slat in the said recesses and securing the frame componentand retainer together using securing means.
 12. A method ofmanufacturing a fire resistant air transfer grille or damper accordingto claim 11, including the step of positioning the retainer so that thesecond edge of each slat is received at either end of the slat in a pairof recesses respectively in opposed wall portions of the retainer sothat the retainer retains each slat in the said recesses of the framecomponent.